Modem composite building material is predominantly made of a combination of wood and plastic. Composite material can be used for various purposes, such as outside decks for houses.
When normal screws are used with such composite materials, the material tends to “mushroom” when the screw is countersunk, leaving a bump above the surface of the board. Conventional screws also tend to split the ends of the boards unless holes are pre-drilled, which is labor intensive. Thus, there is a need for screws for composite materials that reduce both mushrooming and splitting.
In many applications, composite material is fastened to an underlying substrate, such as wood. The fasteners must pass through the composite material and be firmly secured to the substrate.
Accordingly, one object of this invention is to provide new and improved fasteners for composite material.
Another object is to provide new and improved fasteners for composite materials that reduce mushrooming when the fastener is countersunk.
Still another object is to provide new and improved fasteners for composite materials that reduce splitting without pre-drilling.
Yet another object is to provide new and improved fasteners that adequately secure composite material to a substrate.